Process of making hollow drill rods



PROCESS OF MAKING HOLLOW DRLL RODS y Filed Jan. l2. 1922V 3 sheets-sheet 2 INVENTOR A TTORNE Y June 25, 1929. P. A. E. ARMSTRONG 1,718,210

PROCESS OF MAKING HOLLOW DRILL RODS Filed Jan. 12.v 1922 s sheets-sheet 5 Lez ?w/ 6. INVENTOR BY l ATTORNEY l Patented June 25, 1929.

UNITED STATES PATENT OFFICE.

, :BERCY A. E. ARMSTRONG, OF LOUDONVILLE, NEW YORIK, ASSIGNR T L'UDL'UM STEEL COMPANY, OF WATERVLIET, NEW Y0R4I:{, A CORPORATION OF NEW JERSEY.

raocnss oF MAKING iioLLow DRILL Bons.

Application filed January'12,'1922. Serial No. 528,753.

My invention relates to hollow drill rod and other hollow bar products, and will here@ i in be described for affording an understanding of the invention with reference to hollow drill rod for mine drills. The material and process may also be employed in the construction of axles, steam hammer shafts and for many other purposes of like character where there has been experienced with materials lo hitherto available fatigue or progressive cracks starting from a transverse fissure.V

Rock drills made of the hard steel required for rock penetration are subject to breakage from the tremendous vibratorystresses en- .15 countered in use. Such breakage may occur in lvarious ways, as, for example, the drill shaft may break off, or the steel may crack or break radially out from the hollow center, etc..

According to my invention the hard steel of the rock drill is provided with a tough reenforce, as, for example, a reenforce of low car-'- bon steel or other tough material, which serves to prevent breakage without substantial loss of cutting power, and in fact increased cutting power can be obtained, since the provision of the reenforce enables the luse of.

harder steel than could otherwise be used. For example, steel containing over 1% and as high as 1.15% of carbon may be used for the body of the drill rod, While the reenforce may be of mild steel containing under .4% of carbon, as, for example, about .85% of carbon. The Itough reenforce is preferably of generally tubular form, which is best adapted to prevent shaft and radial breaks and give all around strength to the drill steel, but reenforces of various forms may be used.

lin the accompanying drawings, Fig. 1 is a vertical sectional view of an ingot mold arranged for pouring an ingot to be rolled out into hollow drill steel. Fig. 2 is a side view and Fig. 2a an end View of a drill head forged from hollow drill rod embodying my invention. Figs. 3,'4, 5, 6 and 7 are side views, partly in section, of variously formed reenforces for use in the manufacture of drill rod embodying my invention. Figs. 8 and 9 are respectively longitudinal and cross-sectional views of drill rod with an exterior reenforce, and Figs. 10 and 1.1 are cross-.sectibnal views of drill rod with internal reenforces.- Figs.

12 and 13 are vertical sectional views of modified forms of the ingot mold of Fig. 1.

The bore of the drill rod may be obtained in Fig. 6 shows a tube 14g extending slots 15a.

any desired Way-within the'scope of the present invention, but preferably the ingot to be rolled down to drill size comprises a central tube of mild steel welded in place in the ca's'ting of the mgot, as described and claimed in my Patent #1,565,7 71, dated December 15, 1925, and in Fig. 1 I have shown such central tube 10 plugged at its ends as indicated at 11 and 12, and illed with material 13 such as sand, hard burned magnesite, lime, talc, etc., but'which lmay be herein referred to for convemence as sand. Reference numeral 14 represents the reenforeing member of tough material such as low carbon steel, for example, which is preferably placed in the ingot mold between the central tube and the outer wall ofv the mold.; lt may be placed elsewhere, as on the outside of the mold, if desired, as shown at 14, Figs. 8 and 9, and two or more reenforcmg members may be provided, if desired, as shown at 14h, 14, Fig. 11.

The form of the reenforcing member is preferably tubular soas to be well adapted to resist radial breakage extending out from the hollow center, the shaftv and in other directions, but considerable latitude is permissible in the form of the reenforcing members andseveral forms are shown herein as examples. Fig. 3 shows a simple form of tube vreenforce 14d without openings or perforation's of any kind. Fig. 1 shows a similar tube-14, but provided with a plurality of round holes 15. Fig. 4 shows a reenforcing member 14e of expanded metal,

such as commonly used for metal lath, etc.'I Fig., 5 shows a coiled tubular reenforce 14,

andthe coiled material may be of any desired cross-section, as well as the flat'section shown. with longitudinally member 14h made by rolling upa piece of flat sheet metal. The meeting edges ofthe" metal for-reenforce14h Ymay be arranged in various Ways. For example, together at 14i-as shown in Fig. 10,'or they may be separated by a short distance, or may lap over one another, if desired, the last named arrangement being illustrated at 14h in Fig. 7 In Figs. 8 and4 9 the reenforce 14a is placed on the outside of the drill rod;

In the cross sectional view of Fig. 10, I have as well as breakage across- Fig. 7 shows a tubular y they may abut closely shown a drill rod with the customary central opening 10 therein, and having a tubular reenforcing. member 14l substantially midway y between the central opening 10 and the exterior, wall of the drill rod 16.r In Fig. 11 the drill rod 16 has a lined opening 10 formed by welding a tube 10 within the ingot in casting, and is provided with two substantially concentric reenforces 14h, 14. In Figs. 8 and 9 the central opening has a wall. 10 similar to the wall of Fig. 11, and the reenforce 14aL is provided about the exterior of the drill rod. When the reenforcing material is provided by the outside of the drill rod, as shown in Figs. 8 and 9, the removal of such softer material 14a at the drill head, as by 'grinding it y olf either before or after forging the lands,

enables the user to obtain a drill shank of the requisite 'strength and toughness, and at the i same time to obtain a cutting edge free from soft material, and the puter ends of the cutting lands may be readily -brought to correct gauge in grinding off the softymetal 14a.

In pouring the ingot, the molten steel is preferably introduced by means of av pot 17 of .graphite or the like, having outlet holes 18, 19 for the molten metal, and a holder 2O is preferably provided having a recess 21 to receive the pot 17, and having holes 22, 23 in alignmentwith the holes 18, 19 in the pot 17.

',The holder 20 is preferably shouldered at 24 to set within the ingot mold 25, and has a central opening or recess 26 to receive the coretube 10, and is provided with a shoulder 27 to lit within and center the reenforcing tube 14. When the reenforcing member is apertured, as in several of the instances shown, round holes 15 being shown in Fig. 1, 'it may be sufiicient to pour the molten ingot material through holes 18 and 22 outside lthe reenforce 14, and to depend on the passage of molten rolled down is formed around a central tube lco metal through holes 15 to the interior of reen-y forcing tube 14, but where a simple non-apertured reenforcing tube is used, or where the vapertures are not extensive, it is preferable to make provision for entry of the molten metal from the pouring device direct into all the ingot spaces, as, for example, through holes 19 and 23 into the space within the reenforcing tube 14. yWhere a plurality of reenforcing tubes are made use of, as in Fig. 11, for example, additional pouring holes may be provided, as will be readily understood.

Referring to Fig. 12, there is shown an ingot mold arranged for pouring an ingot to be rolled out into hollow drill steel. The bore of the drill'rod may be obtained in any desired way, but preferably the ingot to be 40, and thistube is positioned within the mold, as clearly shown in the drawing. The

`ends of the tube 40 are plugged by means of suitable plugs 41, 42 and its interior filled with a material 43, such as sand, hard burned lInnaggnesite, lime, talc, or the like, but which is p herein referred to for convenience as sand.- 'The reenforcing member of tough material I,comprises a tube 44 formed of low carbon steel, for example, which `is placed in the ingot mold between the central tube 40 and the outer wall of the mold. The lower extremity of the tube 44 is provided with a plurality of notches, such as 45, forming passages between the spa-ces in the mold on either side of the tube 44.

For pouringthe ingot there is provided a pot 47 made of graphite or the like, having outlet holes, such as 48, each of which is in alignment with a corresponding aperture 52 in a pot holder 50. The holder preferably is shouldered at 54 to set within the ingot mold 55 and has a central opening or recess 56 to receive core tube 40. It is also provided with a shoulder 57 to fit within and center the reenforcing tube 44. The holder 50 is provided with a plurality of vent passages, such as 58,- interconnecting the in 'terior of the mold with the atmosphere.

In pouring the ingot the molten steelis` by rolling.

In the modified form of the invention shown in Fig. 13, there is provided a mold similarto that of Figs. 1 and 12, in which there is positioned a' central tube60 having its endsV plugged by suitable plugs 61. and 62, and its interior filled with suitable'lnaterial 63, such as sand or the like. A tube 64 of tough material, such as mild carbon steel, is positioned in the space between the central tube 60 and the outer wall of the mold. The lower end ofthe tube 64 is provided with a plurality of notches 65 forming pasages between the spaces within the mold, partitioned off by the tube 64. A pot 67 .formed of graphite or the like is provided .for theA an annularshoulder 74 for maintaining it in position. The Vholder 70 is provided with a second shoulder 77 arranged to fit within the tube 64 and maintain the tube 64 in'position.. The pot 67 is provided with a plurality of passages, such as 68, through its bottom, each of which is in alignment with a passage 72 extending through therholder 70 andconnecting with the space between tubes 60 and "64. A plurality of vents, such as 78, extend Vthrough the holder 70 and connect one of the spaces 'in the' mold with the atmosphere.

In pouring4 an ingotthe molten metal is introduced by means of the pot 67 and flows through the passages 68 and 72 into the space within the mold between the tubes 60 and 64. It then flows through the passages 65fand upwardly into the space between the tube 64 and outer walls 75 of the mold.

Thus the ingot is formed within the mold land after having beencooled may be elongated to desired -dimensions in any suitable manner.

It is to be understood' that various materials, such as carbon steels and alloy steels, may be used both for the body ofthe ingot and the reenforcing means, so long as the body thereof is adapted to give thecutting or other qualities desired, and the reenforce to give adequate toughness and freedom from breakage.'

A reenforcingtube of nickle, for example, gives good results in making hollow ldrill rod. The reenfor'cing vtube is preferably quite thin, as compared with the body of the f metal, and the molten metal of theingot is or both'.

preferably poured fairly. hot, so that the reenforcing material becomes welded to the.

material of the body of the ingot during the formation of the ingot, or during the rolling down of the ingotto the drill rod size,

ln the making of the-drill rod, the heated ingot is rolled to the desired dimension and the sand removed in known manner, leaving the bore 28 for supplying waterI to the drill head. When the reenforce or reenforces are arranged intermediate the central bore and 'the exterior` of the drill rod and the drill c head is forged out to gauge, the reenforcing material will appear to some extent .in the lands 29 of the drill gauge 30, as indicated at 3l, Fig. 3, but due to deformation in forging and the relatively slight thickness of the `wall of ree-nfoireingJmaterial, which is suf- -cient to prevent breakage, no substantial loss of cutting power is encountered and in drill rod, without v or breaks. l y r l A heat treatment may now be given, eitherl fact cutting power can be increased as harder steel'can now be used for thebody of the being subject to cracks wholly or only on'the bit end, the opposite end or both ends, as desired. A heat treatment which .I have found advantageous'comprises heating'the part or parts'to be' treated to a temperature above that of the transformation point, and rapidly cooling in a cooling medium, such as water or'the like. j

It is'to be understood -that the various forms shownl in the drawings are for illusvtration only, and that changes and modications may be'` resorted to without .departing from my invention, a I cl im: 1. The process of bodies, such as hollow drill rod and the like,

. which comprises casting a 'hollow ingot with a metallic `tubular member in place in the in- `making hollow tubularreenforcing material is welded within the ingot, elongating and reducing the cross-section of the ingot and core, and removing the core. l p

8. The process of making hollow tubular bodies, such as hollow drill rod and the like, which comprises placing in an ingot mold an axially arranged tube, containing a sand core,

rounding said tube and spaced away therelfrom, casting a metallic ingot in said mold 4and a substantially tubular member surwith said tube and member in place therein,

whereby said member is surrounded on all sides by the cast metal, elongating and reducing the cross-section ofthe ingot and core, and removing the sand fromthe tube.v

4. @The process of making hollow drill rod, which comprises casting an ingot of hard steel about a tube of softsteel containing a sand core and an apertured substantially tubular member of soft steel arranged substantially concentrically with said tube by introducing the molten material outside the apertured tubular member and permitting it to pass through the openings therein to `lill the spaced. about the tube, whereby tubular member and. tube become welded within the ingot, elongating and reducing the cross-section of resulting ingot and core, and removing the sand core.

5. rlfhe process of making hollow drill rod and-the like, which comprises casting an ingot of hard steel about a tube of soft steel containing a. sand core and a substantially tubular member lof softsteel arranged substantially i ber and permitting it to pass u der the bottom of the tubular member an then rising up to iill the space about the tube, whereby the. tubular member and the tube become welded within the ingot, elongating and reducing the cross-section of resulting ingot and core, andremoving the sand core..

6. The process of making hollow drill rod and the like, which comprises casting an in. got of yhard steel about a tube of soft steel containing a sandcore and a substantially tubular member of soft steel arranged substantially concentrically with said tube, by introduci g the molten material into the space abort the tube, whereby the tubular member and the tube become welded within the ingot, elongating and reducing the crosssection of resulting ingot and core, and removing the sand core.

7. Process of making hollow drill rod, which comprises arranging an ingot mold with a sand-filled central tube of substantially unhardenable steel, and with an apertured larger substantially concentric tube of substantially unhardenable steel around the central tube and spaced therefrom and from the ingot Walls, casting hardenable steel in the spacewithin the ingot mold about the central tube so that the larger tube is embedded in the cast metal, rolling the ingot, andremoving the sand core, whereby a hollow drill rod is obtained which When made into drills can be hardened and given persisting shar cutting edges and at the sane time be rein orced by -the substantially unhardenable steel portions.

In testimony that I clain'rthe foregoing, I 20 have sigred my name hereto.

PERCY A. ARMSTRONG. 

